RESEARCH HIGHLIGHTS
NATURE|Vol 455|9 October 2008
JOURNAL CLUB
Ben Scheres
Utrecht University, The
Netherlands
David Chavez and his colleagues at the Los
Alamos National Laboratory in New Mexico.
They write that their invention reacted to
impacts, sparks and friction like another
high explosive, PTEN, which melts at more
than 100 °C and is typically moulded as a
solid. They predict that the new compound
will detonate with as much force as the highperformance explosive HMX.
GEOSCIENCES
The melting ocean
Nature Geosci. doi:10.1038/ngeo316 (2008)
After 1997, a glacier that drains 7% of
Greenland’s ice sheet switched from
thickening slowly to thinning quickly, causing
the glacier’s velocity to double. Several
theories have been put forward to explain
the change, including increased lubrication
of the bedrock beneath the glacier. David
Holland of New York University and his team
conclude that it was induced by a sudden rise
in the subsurface ocean temperature along
Greenland’s west coast.
They studied data from laser-altimeter
surveys carried out by aircraft along
120 kilometres of the Jakobshavn glacier, and
oceanographic observations recorded around
the nearby port of Ilulissat. The pulse of
warm water that arrived in 1997 came from
the Irminger Sea near Iceland, they report,
entering the subpolar gyre off Greenland
after the North Atlantic Oscillation weakened
during the winter of 1995–96.
MICROBIOLOGY
A plant scientist finds beauty
in floral arrangements.
Half life
Proc. Natl Acad. Sci. USA doi:10.1073/
pnas.0807707105 (2008)
The exceedingly abundant phytoplankton,
Emiliania huxleyi, has unusual population
dynamics. It can evade viral infection in its
haploid form, when it has only one copy of
each of its chromosomes, but it is susceptible
to the same source of infection during the
diploid part of its life cycle, when its cells
contain twice as much DNA.
Miguel Frada at the Station Biologique in
Roscoff, France, and his colleagues subjected
the phytoplankton to giant phycodnaviruses.
Unlike the diploid cells, the haploid ones did
not burst open — perhaps owing to their
uncalcified membranes somehow preventing
the virus from entering the cells.
Viking mice
ZOOLOGY
Proc. R. Soc. B doi:10.1098/rspb.2008.0958; 10.1098/
rspb.2008.0959 (2008)
Dik dik trick
Mus musculus, the house mouse, has been
colonizing new lands for several thousand
years by hitchhiking with the humans
whose crumbs it has come to rely on. Jeremy
Searle of the University of York, UK, and his
colleagues have used mouse mitochondrial
DNA to retrace human migration.
They write that mice on the northern
and western peripheries of the British Isles,
particularly on the Orkney Islands, share a
genetic lineage with Norwegian mice. These
mice probably arrived with the Vikings —
unlike mice from elsewhere in Britain, which
are genetically more similar to German mice
and probably reflect Iron Age migrations.
House mice on New Zealand, however,
come from a mixture of countries, mirroring
the complex history of migration to the
archipelago from the late eighteenth century
onwards. Before that, New Zealand was
mouse-free.
Behav. Ecol. doi:10.1093/beheco/arn064 (2008)
Of the animals that understand other species’
vocalizations, almost all are social creatures
with complex calls of their own. But ecologists
have identified an eavesdropper that is neither
social nor particularly vocal: the dik-dik.
Daniel Blumstein and his colleagues at
the University of California, Los Angeles,
suspected that Gunther’s dik-dik (Madoqua
guentheri; pictured above), a heavily predated
miniature antelope, could benefit from
eavesdropping. To find out whether it does,
the researchers played alarm calls of the
white-bellied go-away bird (Corythaixoides
leucogaster) and non-alarmist calls from the
slate-coloured boubou (Laniarius funebris)
to a group of dik-diks at the Mpala Research
Centre in Laikaipia, Kenya.
The dik-diks in the study decreased their
foraging and increased their head-turning
only in response to the alarm calls.
W. BOLLMANN/PHOTOLIBRARY
PHYLOGEOGRAPHY
On the face of it, flower arranging
is a fiddly affair, and its underlying
rules are not immediately obvious
to the beholder. But a plant’s
flowers are always arranged in
one of three basic architectures,
or ‘inflorescences’. These take the
form of panicles, loosely but highly
branched clusters in which each
flower has its own stalk (as in the
foxglove); racemes, in which flowers
are arranged individually along an
unbranched, growing stem (the
snapdragon); or cymes, typified
by a cluster of branches at the end
of a stem that each terminate with
flower (the forget-me-not). Simple
rules must lie behind this, and
simple rules are the foodstuff of
mathematical models.
That is the logic behind the work
of Przemyslaw Prusinkiewicz at the
University of Calgary in Alberta,
Canada, and his colleagues. Last
year, they published a model
in which they imagined that
meristems grow into shoots or
flowers according to the value
of a factor that they named ‘veg’
(P. Prusinkiewicz et al. Science 316,
1452–1456; 2007). When veg is
high, a shoot springs forth; when it
is low, a blossom flourishes. Thus,
if over time veg decreases at the
same rate in all of a plant’s growing
tips, the model grows a panicle.
Other simple rules give rise to a
raceme or cyme.
Prusinkiewicz et al. found
that, in Arabidopsis, a gene called
LEAFY influences the value of
veg. But how does this concept
apply to plants with different
architectures? Recently, Erik Souer
of Vrije University in Amsterdam
and his collaborators showed that
modification of LEAFY activity is
crucial for floral architecture in
petunia, a cyme, just as the model
predicts (E. Souer et al. Plant Cell 20,
2033–2048; 2008). They identify a
protein that activates LEAFY only in
developing flower buds and that is
essential for their architecture. I find
the tidy simplicity of these findings
more beautiful than any bouquet.
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